Strut reinforcing structure for a turbine exhaust case

Abstract

A turbine exhaust case (TEC) has an outer case and an inner case structurally interconnected by a plurality of circumferentially spaced-apart struts. At least one of the struts has an airfoil body with a hollow core. The airfoil body has opposed pressure and suction sides extending chordwise from a leading edge to a trailing edge and spanwise from a radially inner end to a radially outer end. The radially inner end of the strut has a strut wall extension that extends through the inner case to a location radially inward of the inner case relative to the central axis.

The invention claimed is: 
     
       1. A turbine exhaust case (TEC) comprising:
 an outer case extending around a central axis; 
 an inner case concentrically disposed inside the outer case, the inner case having a radially outer surface facing away from the central axis and a radially inner surface facing towards the central axis; 
 an annular exhaust gas path radially between the outer case and the inner case; and 
 a plurality of circumferentially spaced-apart struts extending across the annular exhaust gas path and structurally connecting the inner case to the outer case, the plurality of circumferentially spaced-apart struts including a first strut having an airfoil body with a hollow core, the airfoil body having opposed pressure and suction sides extending chordwise from a leading edge to a trailing edge and spanwise from a radially inner end to a radially outer end; 
 wherein the radially inner end of the airfoil body has a strut wall extension that extends through the inner case to a location radially inward of the inner case relative to the central axis, the inner end of the airfoil body connected to the inner case on both the radially inner surface and the radially outer surface of the inner case, wherein the strut wall extension extends in a spanwise direction in continuity to the leading edge and the opposed pressure and suction sides of the airfoil body, and 
 wherein the strut wall extension extends chordwise along only a portion of the opposed pressure and suction sides of the airfoil body. 
 
     
     
       2. The TEC according to  claim 1 , wherein the strut wall extension has a horseshoe cross-sectional shape, and includes a suction side extension segment and a pressure side extension segment extending in a chordwise direction from a leading edge extension segment. 
     
     
       3. The TEC according to  claim 2 , wherein a stiffener ring projects radially inwardly from the radially inner surface of the inner case, the leading edge extension segment of the strut wall extension merging with the stiffener ring. 
     
     
       4. The TEC according to  claim 3 , wherein the annular exhaust gas path has a radial height (D), and wherein a combined length (A) of the stiffener ring and the strut wall extension in a chordwise direction is greater than or equal to half the radial height (D). 
     
     
       5. The TEC according to  claim 4 , wherein the stiffener ring has a length (B), and wherein (B) corresponds to one-third of (A). 
     
     
       6. The TEC according to  claim 5 , wherein the stiffener ring has a radial height (C), and wherein (C) is greater than or equal to two-thirds of (B). 
     
     
       7. The TEC according to  claim 3 , wherein the stiffener ring is monolithically formed with the strut wall extension. 
     
     
       8. The TEC according to  claim 1 , wherein the strut wall extension extends chordwise up to 50% of a total chord length of the airfoil body. 
     
     
       9. The TEC according to  claim 1 , wherein an outer fillet is provided between the airfoil body and the radially outer surface of the inner case, and wherein an inner fillet is provided between the strut wall extension and the radially inner surface of the inner case, the inner fillet being inverted relative to the outer fillet. 
     
     
       10. A TEC comprising:
 an outer case extending around a central axis; 
 an inner case concentrically disposed inside the outer case, the inner case having a radially inner surface facing towards the central axis and a stiffener ring projecting radially inwardly from the radially inner surface; 
 an annular exhaust gas path between the outer case and the inner case; and 
 a plurality of circumferentially spaced-apart struts extending across the annular exhaust gas path and structurally connecting the inner case to the outer case, the plurality of circumferentially spaced-apart struts including a first strut having an airfoil body with a hollow core, the airfoil body having opposed pressure and suction sides extending from a leading edge to a trailing edge, the first strut further having a strut wall extension projecting radially inwardly through the inner case for connection with the stiffener ring on the radially inner surface of the inner case, wherein the strut wall extension has a pressure side extension segment and a suction side extension segment extending in a spanwise direction in continuity to the pressure side and suction side of the airfoil body, the pressure side extension segment and the suction side extension segment projecting in a chordwise direction from a leading edge extension segment, the leading edge extension segment monolithically merging with the stiffener ring, and 
 wherein the strut wall extension has a horseshoe cross-sectional shape. 
 
     
     
       11. The TEC according to  claim 10 , wherein the strut wall extension extends chordwise up to 50% of a total chord length of the airfoil body. 
     
     
       12. The TEC according to  claim 10 , wherein the annular exhaust gas path has a radial height (D), and wherein a combined length (A) of the stiffener ring and the strut wall extension in a chordwise direction is greater than or equal to half the radial height (D). 
     
     
       13. The TEC according to  claim 12 , wherein the stiffener ring has a length (B), and wherein (B) corresponds to one-third of (A). 
     
     
       14. The TEC according to  claim 13 , wherein the stiffener ring has a radial height (C), and wherein (C) is greater than or equal to two-thirds of (B). 
     
     
       15. The TEC according to  claim 10 , wherein the stiffener ring is monolithically casted with the strut wall extension. 
     
     
       16. The TEC according to  claim 10 , wherein the inner case has a radially outer surface facing outward away from the central axis, wherein a first fillet is provided between the airfoil body and the radially outer surface of the inner case, and wherein a second fillet is provided between the strut wall extension and the radially inner surface of the inner case, the second fillet being inverted relative to the first fillet. 
     
     
       17. A turbine exhaust case (TEC) comprising:
 an outer case extending around a central axis; 
 an inner case concentrically disposed inside the outer case, the inner case having a radially outer surface facing away from the central axis and a radially inner surface facing towards the central axis; 
 an annular exhaust gas path radially between the outer case and the inner case; and 
 a plurality of circumferentially spaced-apart struts extending across the annular exhaust gas path and structurally connecting the inner case to the outer case, the plurality of circumferentially spaced-apart struts including a first strut having an airfoil body with a hollow core, the airfoil body having opposed pressure and suction sides extending chordwise from a leading edge to a trailing edge and spanwise from a radially inner end to a radially outer end; 
 wherein the radially inner end of the airfoil body has a strut wall extension that extends through the inner case to a location radially inward of the inner case relative to the central axis, the inner end of the airfoil body connected to the inner case on both the radially inner surface and the radially outer surface of the inner case, and 
 wherein an outer fillet is provided between the airfoil body and the radially outer surface of the inner case, and wherein an inner fillet is provided between the strut wall extension and the radially inner surface of the inner case, the inner fillet being inverted relative to the outer fillet, and 
 wherein each fillet has a radius that provides a smooth transition from the airfoil body to the inner case.